Electrical boxes are used for a variety of applications such as the termination or splicing of electrical wires or the connection to a terminal block or an electrical device. Typically, electrical boxes have a back wall and four or more side walls that define an open side and an interior space. The back wall and side walls can have one or more openings for the passage of wires or cables into the interior or they can be provided with knockouts that can be selectively removed by the user to form the openings. Electrical boxes can be mounted to a structure in a variety of different ways depending on the specific requirements of the user. For some applications, electrical boxes are mounted on the surface of a structure and, for other applications, electrical boxes are mounted in the structure, e.g. inside a wall. Depending on the application and location, electrical boxes can be mounted either in a horizontal or vertical orientation. After the box is installed and the wires entering the box are either spliced together or connected to an electrical device, a cover and/or face plate is secured to the open side of the box.
Due to the varied needs for electrical power and switching, it is sometimes necessary to mount a box outdoors or in a location where it will be exposed to wet conditions. Such installations can include an outdoor receptacle used to provide electricity for lighting, power tools and appliances or an installation for an industrial application. When an application exposes an electrical box to water, it is necessary to design the box so that water does not enter the box and damage the device inside or cause a “short circuit.” An effective way to prevent water from entering an electrical box is to install a cover over the faceplate. In addition, a gasket for the cover and seals for the openings in the walls of the box can provide a weatherproof enclosure.
Some of the weatherproof electrical boxes currently in use are metallic boxes that are constructed from a die cast metal such as aluminum or zinc. These boxes have a rigid construction and protect the devices and wiring housed inside from dirt and moisture as well as physical abuse. FIGS. 1 and 2 show a typical metallic box 910 with two side walls 912, 914 and two end walls 916, 918 extending from a back wall 920 to define an interior 922 and an open front side 924. The opposing end walls 916, 918 and the back wall 920 each have a threaded opening 926, 928 and 930, respectively, for receiving a fitting or conduit (not shown). The box 910 also has two faceplates 932, 934 (FIG. 1) extending from the end walls 916, 918 on the open front side 924 of the box 910, which are used for mounting electrical devices 935 (FIG. 2) such as receptacles and switches. The back wall 920 has a grounding boss 936 with a threaded aperture 938 that extends into the interior 922 and is used to receive a screw for securing a ground wire (not shown). FIG. 2 shows a cover 940 with two hinged lids 942, 944 attached to the open side 924 of the metallic box 910 to protect the receptacle 935 mounted in the box 910 from dirt and moisture when the receptacle 935 is not being used. A tab 946 with an aperture 948 extends outwardly from the exterior of the side wall 912 and is substantially coplanar with the exterior surface of the back wall 920. The aperture 948 is used for mounting the box 910 to a structure using a screw or bolt (not shown).
The outdoor metallic boxes currently in use generally have two designs for attaching the box to a structure. The first design attaches arms to at least two corners of the box (four may be needed for some installations) using small screws. Each arm typically has three holes—two for the small screws that attach the arm to the box and one for a larger screw that fastens the arm to the structure. The two small screws tend to strip and are difficult to seat in the tapped apertures in the box.
In another design, the metallic box has integral arms that are formed in four to eight locations at the corners of the box. The arms and the box are a formed as a single component part and the arms allow the user to install the box on a structure. The box is easy to install but has an irregular profile since the arms protruding from the corners are not flush with the surface of the side walls.
The prior art outdoor metallic boxes are designed to be used with standard size conduits and fittings. The boxes are generally constructed from zinc or aluminum using a die-casting process or another molding method. Typically, the end of the conduit is threaded (i.e., the “male end”) and the outdoor metallic box has a threaded opening for receiving the conduit (i.e., the “female end”). In most cases, all of the openings in the box for connecting conduits are the same size. For example, all of the conduit connections for the box can be ½-inch or ¼-inch NPT (National Pipe Thread). Only one size conduit with a diameter and thread size that matches the opening can be connected to the box. If a larger or smaller diameter (e.g., from a ½-inch to a ¼-inch diameter) conduit is used, an entirely new box would be needed with a different diameter and different female mating threads. In order to use a box with a different size connection, an adapter fitting is needed to either increase or reduce the size of the conduit connection. This increases the cost of the materials and labor for installing an outdoor metallic box. In cases where a larger connection is needed (e.g., a 1-inch NPT), the user could drill a larger hole and tap new threads but this is prohibitively expensive.
The outdoor metallic boxes currently in use are limited because they typically can only be connected to conduits of a single size. As a result, the user must stock boxes with different size connections to accommodate different size conduits. This is expensive and inconvenient for the user.
The outdoor metallic electrical outlet boxes that are currently in use generally have two or more openings in the side walls or back wall that can be used for connecting conduits or fittings. The boxes have a standard number of threaded openings and, after they are installed, the user blocks off the unused openings with a metal or plastic plug. The plug typically has a cut out trench or groove on the top surface of the plug that allows the plug to be rotated using a screw driver. The plug is screwed into the unused opening until it is securely held in place by the threads. The installation of the plugs in the unused openings of the box adds more components to the overall product and requires additional steps for the end user. In order to provide a watertight seal, the plug threads must be coated with a sealant before the plug is inserted in the opening, which adds additional steps and cost to the installation.
Accordingly, there is a need for an outdoor metallic electrical outlet box that can be mounted to a structure without requiring additional mounting hardware that extends from or is connected to the side walls of the box. There is also a need for an outdoor metallic box that can be connected to different size conduits without requiring an adapter fitting or reworking. In addition, there is a need for an outdoor metallic electrical outlet box that has plugs for unused connections that can be easily installed by the manufacturer and easily removed by the user.